Mean girls (and boys) and biology

A new study by researchers at University of Texas at San Antonio and University of Minnesota, school of management, shows that during the week of their ovulation, women subconsciously become more competitive about their socio-economic standing in comparison to other women, and are less likely to help them. “They become meaner to other women”, says Kristina Durante, assistant professor of marketing at UTSA, and the principal investigator of the study.

Durante and her group were interested in this topic because of findings from a previous study that asked female volunteers a very simple, yet, profound question: a new job offer comes with two options. Option A, you get $100,000 in salary per year, but your peers get $200,000 per year or, option B, you get $50,000 per year, and your peers get $25,000 per year. Which option do you prefer?

Surprisingly, more than half (56%) of the female volunteers who were asked this question chose option B. They were willing to take substantial pay cut, if it meant that they would make relatively more money than their peers. Durante was intrigued by this result, and wondered what was different between these women and the remaining 44%, who chose absolute gains over relative.

Durante and group reasoned that the answer might be have to do with sexual competition, and hypothesized that ovulatory status could account for the increase in a woman’s sense of economic competition with other women. They tested their hypothesis through various behavioral tests of 309 female volunteers, who were categorized in either the “high- fertility group” or “low-fertility group,” based on self-reported ovulation status.

In the first behavioral test, volunteers were asked to choose between options of having an expensive car, with other women getting an even more expensive car, or having a cheaper car, with other women having an even cheaper car. Consistent with their hypothesis, the majority of women in the high fertility (ovulating) group chose the option that gave them relative gains by choosing a cheaper car, while majority of women in the low-fertility group (non-ovulating) chose the option of absolute gain by choosing the more expensive car.

This phenomenon was even more pronounced in the results of the dictator game, a test where female volunteers were given a fixed amount of money and asked to divide it between themselves and another person. In this scenario, urinalysis was used to definitively determine fertility status.

As expected, ovulating women gave significantly less money to other women, than non-ovulating women. Interestingly, ovulating women were more likely to give significantly more money to a man, as much as 50%, than were non-ovulating women.

The study very clearly demonstrates that the fertility status of a female can significantly alter her economic decisions, and her interactions with other women, as well as men, an observation that makes intuitive sense. Intriguingly, a study by Buunk et al. (2012) showed that in a similar game of resource sharing, men behaved more competitively and less prosocially towards other men, than they did towards women. Thus, it seems that when it comes to sexual competition, it’s not just girls who can be mean, but also boys!